Navigation systems are used by people and vehicles for routing and directions in order to travel between two locations. Navigation systems require accurate information to properly route vehicles. Identifying exactly where a vehicle is on the road in real time, along with its immediate surroundings, may eliminate many dangerous unknowns. Further, a comprehensive map is a crucial component of assisted or automatic driving. Vehicles may include many sensors, but a comprehensive map may be the most important tool vehicles use. Sensors in vehicles may be able to detect lanes and lane markings in real time using image processing and Lidar based systems. These systems are useful for obstacle avoidance and detecting the movements of other vehicles. When used alone though, on board sensor systems may exhibit large blind spots and may be unable to predict events or maneuvers even a short distance away, i.e. out of range of the vehicle's sensors.
On-board sensors, however, when combined with comprehensive maps may allow for assisted and highly automated vehicle operation. A comprehensive map and an associated geographic database may be made up of information or data observed in real-time or measurements gathered over time. The geographic database may include information about the represented geographic features, such as the positions of the roads, speed limits along portions of roads, address ranges along the road portions, turn restrictions at intersections of roads, direction restrictions, such as one-way streets, and so on. Information for the geographic database may be collected, sorted, and analyzed in order provide accurate estimations for the roadway.